Scorecard's information about chemical use is derived from the Use Clusters Scoring System, developed by EPA's Office of Pollution Prevention and Toxics. This system groups chemicals into use clusters, identifying sets of chemicals that are substitutes for each other in particular applications. Specific applications are defined based on functional use categories, which have been developed by the European Economic Community (EEC, 1991). Chemicals can perform a variety of functions as adhesives, aerosol propellants, bleaching agents, electroplating agents, fuel additives, oxidizing agents, semiconductors, solvents, etc. The UCSS currently contains data on nearly 400 use clusters and 4,700 chemicals.

Unfortunately, EPA's Use Clusters do not identify many uses that are important sources of exposure to toxic chemicals for the general public. Use clusters do not directly correspond to types of consumer products, so it is currently not possible to identify which chemicals are used in household cleansers, for example. Use clusters also do not identify chemicals that are pesticides or drugs.

The Use Cluster Scoring System covers chemical uses by a variety of industrial and commercial sectors. It includes more industrial sectors than are covered by the Toxic Release Inventory, and provides data on use volume and environmental releases for chemicals by cluster. It does not provide disaggregated data that could be used to characterize chemical use or release at specific facilities or in specific geographic areas.

Once member chemicals for a cluster are identified, EPA combines information on potential human and ecological hazards and exposures, pollution prevention potential, and regulatory coverage in order to score chemicals and clusters into high-, medium- and low-concern categories. The system provides a measure of potential risk based on available data, and is a useful screening tool for setting priorities for risk reduction or pollution prevention activities. Use cluster scores, for example, can provide an initial indication of potentially safer substitutes for toxic chemicals used for specific functions.

EPA, Office of Pollution Prevention and Toxics. Use Clusters Scoring System. Industrial use data were obtained from UCSS software: Use Clusters Scoring System (Version 3.0, Windows Prototype 3). November 1996.

SAB. An SAB Report: Improving the Use Cluster Scoring System. EPA-SAB-EEC-95-017. Science Advisory Board, EPA, Washington, DC. 1995.

EEC. Members of the Sub-group "Use Categories" in the context of Directive 79/831/EEC. Nuclear Safety and Civil Protection, Commission of the European Communities Directorate. 1991.